A rising demand for food in emerging market economies has further contributed to grain shortages.

The International Monetary Fund (IMF) has calculated that corn ethanol production in the US accounted for at least half the rise in world corn demand in each of the past three years.

Washington

provides a subsidy of $0.51 per gallon to ethanol blenders and imposes a tariff of $0.54 per gallon on imports.

In the European Union (EU), most countries exempt biofuels from some gas taxes and impose an average tariff equal to more than $0.70 per gallon of imported ethanol.

Historic levels

Robert Zoellick, president of the World Bank, said on Thursday that while people in developed nations complained about the high cost of fuel to run their cars, poor people in developing nations were struggling to feed themselves.